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Morphological Aspects of Human Blastocysts and the Impact of Vitrification Ebner T, Vanderzwalmen P, Shebl O, Mayer RB, Moser M Tews G J

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Morphological Aspects of Human Blastocysts and the Impact of Vitrification Ebner T, Vanderzwalmen P, Shebl O, Mayer RB, Moser M Tews G J Journal für Reproduktionsmedizin und Endokrinologie – Journal of Reproductive Medicine and Endocrinology – Andrologie • Embryologie & Biologie • Endokrinologie • Ethik & Recht • Genetik Gynäkologie • Kontrazeption • Psychosomatik • Reproduktionsmedizin • Urologie Morphological Aspects of Human Blastocysts and the Impact of Vitrification Ebner T, Vanderzwalmen P, Shebl O, Mayer RB, Moser M Tews G J. Reproduktionsmed. Endokrinol 2011; 8 (1), 13-20 www.kup.at/repromedizin Online-Datenbank mit Autoren- und Stichwortsuche Offizielles Organ: AGRBM, BRZ, DVR, DGA, DGGEF, DGRM, D·I·R, EFA, OEGRM, SRBM/DGE Indexed in EMBASE/Excerpta Medica/Scopus Krause & Pachernegg GmbH, Verlag für Medizin und Wirtschaft, A-3003 Gablitz FERRING-Symposium digitaler DVR 2021 Mission possible – personalisierte Medizin in der Reproduktionsmedizin Was kann die personalisierte Kinderwunschbehandlung in der Praxis leisten? Freuen Sie sich auf eine spannende Diskussion auf Basis aktueller Studiendaten. SAVE THE DATE 02.10.2021 Programm 12.30 – 13.20Uhr Chair: Prof. Dr. med. univ. Georg Griesinger, M.Sc. 12:30 Begrüßung Prof. Dr. med. univ. Georg Griesinger, M.Sc. & Dr. Thomas Leiers 12:35 Sind Sie bereit für die nächste Generation rFSH? Im Gespräch Prof. Dr. med. univ. Georg Griesinger, Dr. med. David S. Sauer, Dr. med. Annette Bachmann 13:05 Die smarte Erfolgsformel: Value Based Healthcare Bianca Koens 13:15 Verleihung Frederik Paulsen Preis 2021 Wir freuen uns auf Sie! Blastocyst Morphology Morphological Aspects of Human Blastocysts and the Impact of Vitrification T. Ebner1, P. Vanderzwalmen2, O. Shebl1, R. B. Mayer1, M. Moser1, G. Tews1 The topic whether blastocyst culture and transfer is a promising tool in IVF laboratories has been discussed controversially. Discrepancies in outcome may be explained by the fact that formation of a blastocyst on day 5 does not automatically correspond to its viability. Adequate morphological scoring at blastocyst stage (quality of inner cell mass and trophectoderm, expansion, screening for anomalies) would definitely help to significantly reduce the number of blastocysts being replaced, which in turn would limit the number of multiple gestations. Such a strategy could automatically increase the number of blastocysts to be frozen for later replacement. Currently, vitrification challenges slow freezing as the cryopreservation method of choice, since it is faster, more cost-effective and yields at least comparable thawing results. With respect to this, four morphological parameters of vitrified/warmed blastocyts are reported (re-expansion, hatching, necrotic foci and cytoplasmic defects) which can successfully be used for selection purposes in frozen blastocyst transfer. To conclude, blastocyst culture, transfer and cryopreservation is certainly a valuable method in the hands of IVF practitioners and has gained acceptance by many programs throughout the world. Key words: blastocyst quality, hatching,inner cell mass, re-expansion, vitrification Morphologische Analyse der Blastozyste und Einfluss der Vitrifikation. Die Meinungen, ob eine Blastozystenkultur bzw. ein Blastozystentransfer vielversprechende Methoden der assistierten Reproduktion sind, gehen auseinander. Ein möglicher Grund für diese Diskrepanzen könnte die Tatsache sein, dass die Bildung einer Blastozyste am 5. Entwicklungstag nicht automatisch bedeutet, dass diese auch vital ist. Eine adäquate morphologische Beurteilung im Blastozystenstadium (Qualität von innerer Zellmasse und Trophektoderm, Expansion, Anomalien) würde sicherlich einer Reduktion der Zahl der zu transferierenden Blastozysten förderlich sein und so weiter zur Verringerung der Mehrlingsschwangerschaften beitragen können. Damit einhergehend würde die Anzahl der zu kryokonservierenden Embryonen natürlich steigen. Um eine exakte Prognose hinsichtlich einer zu erwartenden Implantation nach dem Tauen/Erwärmen erstellen zu können, bieten sich 4 morphologische Parameter zur Selektion ehemals kryokonservierter Blasto- zysten an: Re-Expansion, Hatching, das Vorhandensein nekrotischer Areale sowie zytoplasmatische Defekte. Zusammenfassend lässt sich behaupten, dass bei detaillierter morphologischer Analyse der Blastozyste deren Kultur, Transfer und Kryokonservierung sehr wohl eine Berechtigung auf dem Gebiet der künstlichen Befruchtung hat. J Reproduktionsmed Endokrinol 2011; 8 (1): 13–20. Schlüsselwörter: Blastozystenqualität, Hatching, innere Zellmasse, Re-Expansion, Vitrifikation Introduction delivery, is non-invasive morphological phectoderm (TE) responsible for the ac- selection at different developmental cumulation of fluid in the blastocyst cav- Compared to the natural cycle, the situa- stages [3, 4]. ity and specialised for implantation and tion in IVF is different because con- an inner cell mass (ICM) forming all trolled ovarian hyperstimulation may Theoretically, any prolongation of in three germ layers of the fetus. cause accidental maturation and ovula- vitro culture up to day 4 or day 5 will tion of germ cells of reduced develop- allow for a more accurate prediction of Morphology before Vitrifi- mental potential. In other words, the ac- developmental capacity. On day 4 (90– tual implantation potential may be over- 100 hours past insemination), blasto- cation estimated though oocyte morphology, meres should have formed numerous Continual improvement in culture media fertilization and cleavage rate may ap- tight intracellular junctions finally re- composition resulting in a higher number pear inconspicuous at first glance. On sulting in a compacting or even a moru- of available day 5 embryos had 2 major the other hand, even embryos of worst la-stage embryo. This marks the switch consequences for embryologists. On the quality may sometimes turn out to be from a cell cluster of individual blas- one hand, adequate cryopreservation viable, e.g. develop to healthy babies. tomeres to a relatively smooth mass with programs for blastocysts had to be estab- indistinguishable cell outlines capable of lished, and, on the other, there was a need However, taken into consideration that actively regulating its internal environ- for more detailed blastocyst scoring sys- usually routine laboratories neither have ment. On the fifth day of in vitro culture tems in order to filter out those blastocysts the equipment nor the resources to ana- (114–120 hours) preimplantation devel- which would implant preferentially. lyze embryo metabolism [1, 2] or cyto- opment should culminate in the forma- genetical constitution, the only approach tion of the blastocyst. Once fully devel- At the beginning of efficient blastocyst to reach the ultimate goal in assisted re- oped human blastocysts consist of two grading some twenty years ago particu- production, namely a healthy singleton different cell types: an outer layer of tro- lar attention was focused on develop- Received: July 15, 2010; accepted after revision: January 31, 2011 From the 1Landes- Frauen- und Kinderklinik, IVF-Unit, Linz, Austria, and the 2Centre Hospitalier Inter Regional Cavell (CHIREC), Brussels, Belgium and IVF Centers Prof. Zech, Bregenz, Austria Correspondence: Thomas Ebner, PhD, Landes- Frauen- und Kinderklinik, Kinderwunsch Zentrum Linz, A-4020 Linz, Krankenhausstraße 26–30; e-mail: [email protected] J Reproduktionsmed Endokrinol 2011; 8 (1) 13 For personal use only. Not to be reproduced without permission of Krause & Pachernegg GmbH. Blastocyst Morphology mental stage, e.g. blastocyst expansion Though it has been suggested [13] that the lineage that gives rise to the fetus [5, 6]. A more recent scoring system [7] indirect assessment of the total cell num- [22]. took additional morphological features ber (TCN) without destroying the blasto- into consideration, namely grade of ex- cyst is possible under good inverted Cell Lineages pansion and morphology of ICM and optics, the vast majority of studies on Hardy et al. [15] were one of the first to TE. According to the degree of expan- TCN were performed using stained cells realize certain interesting differences in sion the blastocysts were scored using of spare embryos of reduced quality (do- the growth rate of both cell lineages. In Roman numbers in ascending order nated to research), thus, probably not general, mitotic rate of the trophecto- ranging from grade I (blastocyst cavity representing the actual cell number of derm is approximately 1.5 times higher less than half of the volume of the em- healthy blastocysts. Early work on TCN than that of the ICM; however, com- bryo) to VI (completely hatched blasto- faced another drawback, namely the in- pared to some other mammals, the over- cyst). Beginning with full blastocyst ability of simple culture media (e.g. all proportion of the inner cell mass is stage (grade III) additional assessment Earle’s balanced salt solution, Ham’s relatively high, e.g. 34% of all cells on of ICM and TE was performed (based on F10, medium T6) to adequately support day 5, 51% on day 6 and 37% on day 7 cell number and cohesion) in order to human embryo development in vitro. [15]. The striking peak on day 6, with predict developmental competence. Apart from achieving lower blastocyst half of all cells in the blastocyst being formation rates [14] these authors some- part of the ICM, is explained by an in- Though the Dokras system [5, 6] was how underestimated mitotic potential of crease in ICM growth rate between days shown to be helpful in routine laboratory in vitro grown blastocysts. 5 and 6, a time when the number of TE work [8] the more detailed Gardner ap- cells
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